👤 Susanne Flach

Patients with metabolic syndrome and heart failure (HF) often have accompanying kidney dysfunction, which was recently defined as cardiovascular-kidney-metabolic (CKM) syndrome. Prior metabolomics profiling of metabolic syndrome patients identified a plasma branched chain amino acid (BCAA) signature, and BCAAs themselves are elevated in the myocardium of patients with HF, potentially due to a defect in BCAA catabolic breakdown. The rate limiting step of BCAA catabolism is the decarboxylation by the enzyme branched chain ketoacid dehydrogenase (BCKDH), which is negatively regulated by BCKDH kinase (BCKDK or BDK), and BDK inhibitors improve metabolism and heart failure preclinically. Here, using two pre-clinical CKM models, the hyperphagic ZSF1 obese rat and the uninephrectomized SDT fatty rat with high salt drinking water, we applied unbiased proteomic, transcriptomic and metabolomic profiling to assess overall kidney gene expression and mitochondrial function. We show that BCAA catabolic impairment is associated with and may be causal to CKM and demonstrated impairment in BCAA catabolism within ZSF1 obese rat kidneys. In both CKM animal models, treatment with the BDK inhibitor BT2 improved urine protein content, kidney hypertrophy, and kidney pathology. Furthermore, coadministration of BT2 and the sodium-glucose cotransporter-2 inhibitor empagliflozin demonstrated additive effects to improve kidney parameters, kidney gene expression signatures, and kidney mitochondrial density and function. Our study suggests that in addition to its previously reported beneficial effects on metabolism and cardiac function, BDK inhibition may also improve kidney health and therefore could represent a new therapeutic avenue for CKM. Show less

Inhibition of branched-chain ketoacid dehydrogenase kinase (BDK or BCKDK), a negative regulator of branched-chain amino acid (BCAA) metabolism, is hypothesized to treat cardio-metabolic diseases. From a starting point with potential idiosyncratic toxicity risk, modification to a benzothiophene core and discovery of a cryptic pocket allowed for improved potency with 3-aryl substitution to arrive at PF-07328948, which was largely devoid of protein covalent binding liability. This BDK inhibitor was shown also to be a BDK degrader in cells and in vivo rodent studies. Plasma biomarkers, including BCAAs and branched-chain ketoacids (BCKAs), were lowered in vivo with enhanced pharmacodynamic effect upon chronic dosing due to BDK degradation. This molecule improves metabolic and heart failure end points in rodent models. PF-07328948 is the first known selective BDK inhibitor candidate to be examined in clinical studies, with Phase 1 single ascending dose data showing good tolerability and a pharmacokinetic profile commensurate with once-daily dosing. Show less

Parallel to major changes in fatty acid and glucose metabolism, defect in branched-chain amino acid (BCAA) catabolism has also been recognized as a metabolic hallmark and potential therapeutic target for heart failure. However, BCAA catabolic enzymes are ubiquitously expressed in all cell types and a systemic BCAA catabolic defect is also manifested in metabolic disorder associated with obesity and diabetes. Therefore, it remains to be determined the cell-autonomous impact of BCAA catabolic defect in cardiomyocytes in intact hearts independent from its potential global effects. In this study, we developed two mouse models. One is cardiomyocyte and temporal-specific inactivation of the E1α subunit (BCKDHA-cKO) of the branched-chain α-ketoacid dehydrogenase (BCKDH) complex, which blocks BCAA catabolism. Another model is cardiomyocyte specific inactivation of the BCKDH kinase (BCKDK-cKO), which promotes BCAA catabolism by constitutively activating BCKDH activity in adult cardiomyocytes. Functional and molecular characterizations showed E1α inactivation in cardiomyocytes was sufficient to induce loss of cardiac function, systolic chamber dilation and pathological transcriptome reprogramming. On the other hand, inactivation of BCKDK in intact heart does not have an impact on baseline cardiac function or cardiac dysfunction under pressure overload. Our results for the first time established the cardiomyocyte cell autonomous role of BCAA catabolism in cardiac physiology. These mouse lines will serve as valuable model systems to investigate the underlying mechanisms of BCAA catabolic defect induced heart failure and to provide potential insights for BCAA targeted therapy. Show less

The mammalian mitochondrial branched-chain ketoacid dehydrogenase (BCKD) complex is a multienzyme complex involved in the catabolism of branched-chain amino acids. BCKD is regulated by the BCKD kinase, or BCKDK, which binds to the E2 subunit of BCKD, phosphorylates its E1 subunit, and inhibits enzymatic activity. Inhibition of the BCKD complex results in increased levels of branched-chain amino acids and branched-chain ketoacids, and this buildup has been associated with heart failure, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. To find BCKDK inhibitors for potential treatment of these diseases, we performed both NMR and virtual fragment screening and identified tetrazole-bearing fragments that bind BCKDK at multiple sites. Through structure-based virtual screening expanding from these fragments, the angiotensin receptor blocker class antihypertension drugs and angiotensin receptor blocker-like compounds were discovered to be potent BCKDK inhibitors, suggesting potential new avenues for heart failure treatment combining BCKDK inhibition and antihypertension. Show less

We conducted a meta-analysis of three endometrial cancer genome-wide association studies (GWAS) and two follow-up phases totaling 7,737 endometrial cancer cases and 37,144 controls of European ancestry. Genome-wide imputation and meta-analysis identified five new risk loci of genome-wide significance at likely regulatory regions on chromosomes 13q22.1 (rs11841589, near KLF5), 6q22.31 (rs13328298, in LOC643623 and near HEY2 and NCOA7), 8q24.21 (rs4733613, telomeric to MYC), 15q15.1 (rs937213, in EIF2AK4, near BMF) and 14q32.33 (rs2498796, in AKT1, near SIVA1). We also found a second independent 8q24.21 signal (rs17232730). Functional studies of the 13q22.1 locus showed that rs9600103 (pairwise r(2) = 0.98 with rs11841589) is located in a region of active chromatin that interacts with the KLF5 promoter region. The rs9600103[T] allele that is protective in endometrial cancer suppressed gene expression in vitro, suggesting that regulation of the expression of KLF5, a gene linked to uterine development, is implicated in tumorigenesis. These findings provide enhanced insight into the genetic and biological basis of endometrial cancer. Show less